Program Director/Principal Investigator (Last, First, Middle): Moore, John PROJECT SUMMARY (See instructions): This application is for the renewal of R01 AI45463 "Modified envelope glycoproteins for HIV-1 vaccine", a grant first awarded in 1999, re-awarded in 2004, and now being re-competed. Our goals remain the same: To design vaccines intended to induce neutralizing antibodies (NAbs), based on accumulated and emerging knowledge of structure-function relationships within the HIV-1 Env complex. In this application for 2 years support under the ARRA funding program we have revised our Specific Aims to focus on two sub-projects that we believe can be successfully accomplished within 2 years, and that do not overlap with a HIVRAD Program Project award that will soon be made and in which we direct Project 1 (P01 AI082362-01;Structure and immunogenicity of cleaved, stabilized HIV-1 envelope trimers; Principal Investigator, William C. Olson). We now propose 3 shortened and simplified Specific Aims. Specific Aim 1: SOSIP gp140 proteins based on CCR5-inhibitor resistant variants with altered Env configurations. We will make SOSIP gp140 proteins based on resistant variants CC101.19 (with gp120 V3 changes) and D1/85.16 (with gp41 fusion peptide changes), study their ability to form trimers and present NAb epitopes, provide them to Dr. Sriram Subramaniam for structural studies, and prepare them for immunogenicity studies in mice (Aim 3). Specific Aim 2: To study in vitro how to overcome immunosuppressive effects of gp41 sequences by the use of adjuvants and TLR activators. We will collaborate with Dr. Min Lu to design, synthesize and evaluate soluble peptide mimetics of the "immunosuppressive peptide" (ISP) region of gp41, in vitro. Our endpoints will include the inhibition of cellular proliferation and the release of potentially suppressive cytokines. By modifying the ISP sequence, we will identify the residues that are responsible for the suppressive effects we observe. We will also evaluate whether the suppressive effects of ISP motifs can be overcome in vitro, by the use of TLR activators and other adjuvant-associated molecules. Specific Aim 3: Evaluating the immunogenicity of the novel SOSIP gp140 proteins and the immunosuppressive effects of the gp41 ISP domain in mice. We will conduct immunogenicity studies in mice that are intended to explore whether the novel SOSIP gp140 proteins based on CCR5 inhibitor- resistant viruses (see Aim 1) are superior immunogens, compared with their parental strain. We will also explore whether the optimal ISP peptide sequence identified in Aim 2 can suppress immune responses to co-administered Env and Gag proteins, and whether any such suppressive effect can be overcome by the use of an appropriate adjuvant or TLR activator (see Aim 2). RELEVANCE (See instructions): PROJECT/PERFORMANCE SITE(S) (if additional space is needed, use Project/Performance Site Format Page) Project/Performance Site Primary Location Organizational Name: Weill Cornell Medical College DUNS: 060217502 Street 1: 1300 York Avenue Street 2: City: New York County: State: New York Province: Country: USA Zip/Postal Code: 10065 Project/Performance Site Congressional Districts: 14 Additional Project/Performance Site Location Organizational Name: DUNS: Street 1: Street 2: City: County: State: Province: Country: Zip/Postal Code: Project/Performance Site Congressional Districts: PHS 398 (Rev. 11/07) Page 2 Form Page 2